Is it possible to have 1 of ea kind of ship generated at the start of ea game play?

You could edit the S0_SurveyShip.shipcfg to point to the right hull and edit the components of the SurveyShip in GC2Ships.xml but this would just replace the survey ship. I don't know of another way to spawn a single (unique!) ship.

Only with a scenario, not in "normal" mode, but basically yes. I'd also suggest, if you do this, to also change the core ships to not be so sucktastic.

I could see this being interesting for a kind of 'Midway Campaign' scenario. Say you start with your usual building capacities, so you can make transports and small/heavy fighter-sized things, but you begin with a couple cruisers and one battleship. These can be massively important weapons at the start of the game, but if you lose them, or if you manage to kill one of the enemy 'capitol ships', then that is a highly decisive loss or gain.

Or you could just make all hull types available at the start of the game, but make progressively better hulls even more expensive, that too could make for an interesting scenario. Bigger ships have an inherent advantage, even if they're packed with extremely low-tech weapons and defenses their higher HPs are extremely important, so they could be worthwhile to build.. but with weak starting economies and limited shipyard capacities they couldn't become the standard battleline vessel for quite some tiem yet.